This program is directed at the analysis of peptide hormone receptors in testis and ovary, with particular reference to the control of receptor concentration by changes in homologous and heterologous hormones. Desensitization of gonadal adenylate cyclase and steroidogenic responses by gonadotropic hormones is followed by receptor loss and turnover or processing of the hormone-receptor complex. These processes are investigated in Leydig cellsand ovarian granulosa cells to determine the effects ofhormone-induced receptor regulation on gonadal responsiveness, and to analyze the mechanism and consequences of target-cell desensitization. The receptors and direct actions of gonadotropin-releasing hormone (GnRH) in the ovary and testis are also analyzed. The effects of FSH on granulosa-cell maturation were shown to be mediated by cyclic AMP, and the inhibitory actions of GnRH agonists on this process were associated with decreased cAMP production. GnRH receptors in the granulosa cell were shown to mediate the minor stimulatory effects of GnRH on ovarian function, as well as the most prominent anti-gonadal actions of GnRH in the ovary.